My favorite are Lulu and ChaCha because of the interchangeable snaps. I don't have to have a million headbands, and can just get a new band when her head grows or switch to clips if she ever grows hair and I can keep using the bows/buttons I already bought.
I just ordered from this one. I've been admiring their headbands for a while now - I wanted something to make DD look feminine without over-the-top flowery stuff. www.etsy.com/shop/littlehighbury
ditto lulu and chacha, pretty much exclusively use them. We probably have 15-20 hair accessories and then I just size up in band size as needed (and at 2 my kid wears adult size bands...)